In the Get Url add this to the URL box:
javascript:window.open('YOURURL.html",'NAME','width=###,height=###,left=###,top=###,scrollbars=??,resizable=??,status=??,menubar=??,location=??,toolbar=??');
Change YOURURL.html with your own. NAME is anything you want. The ### must be a numerical value in pixels.
The ?? must be 1 (yes) or 0 (no)
NOTE= You don't need to write all the options but if you don't write the resizable, location and toolbar options, their value will be 0 by default. So you won't see them. The default for scrollbars, status and menubar is 1
Good luck.